Introduction

The 30YearWeather API provides aggregated historical weather data derived from NASA POWER satellite observations (1991-2024). Unlike standard forecast APIs that predict the next 14 days, our API tells you what the weather is statistically likely to be on any day of the year.

30-Year Baseline

Averages, extremes, and probabilities calculated from 3 decades of data.

373 Destinations

Global coverage of major tourist cities, expanding regularly.

AI-Ready

OpenAPI 3.1 spec, LLM discovery files, and context-optimized responses.

🎓DOI: 10.5281/zenodo.13579246

Permanent Identifier for Academic Use

📖 How to Cite This API

Academic Citation (APA 7th)

30YearWeather. (2026). Historical Weather API [Computer software]. Retrieved from https://30yearweather.com/api-docs. Data source: NASA POWER Project (1991-2021)

IEEE Style

30YearWeather, "Historical Weather API," 2026. [Online]. Available: https://30yearweather.com/api-docs. Data: NASA POWER (1991-2021).

BibTeX

@misc{30yearweather2026,
  title = {Historical Weather API},
  author = {{30YearWeather}},
  year = {2026},
  url = {https://30yearweather.com/api-docs},
  note = {Data source: NASA POWER Project (1991-2021)}
}

Data Attribution: This API provides weather data derived from NASA POWER Project satellite observations. When publishing research using this data, please cite both 30YearWeather API and the original NASA POWER data source.

For Educators & Researchers

Free for Academic Use

The 30YearWeather API is free for educational and non-commercial research. We support students and researchers with:

No API key required
10,000 requests/day for university IPs
Bulk data exports available
Citation support

Climate Science

Analyze 30-year temperature anomalies and study urban heat island effects using our granular daily data.

Statistics & Data Sci

Perfect dataset for teaching time-series forecasting, regression models, and probability analysis.

Quick Start

Get Prague weather summarycURL

curl "https://30yearweather.com/api/v1/city/prague?minified=true"

No API key required for the free tier. Just send HTTP requests and get JSON responses.

💻 Code Examples

import requests
import pandas as pd

# Fetch 30 years of Tokyo December data
url = "https://30yearweather.com/api/v1/historical"
# Note: In actual API, use /city/tokyo or /weather/tokyo/{date}
# This conceptual example matches the documentation request

response = requests.get("https://30yearweather.com/api/v1/city/tokyo")
data = response.json()

# Citation
print("Data source: 30YearWeather API")
print("https://30yearweather.com/api-docs")

API Endpoints

GET/api/v1/city/:slug

Returns a comprehensive climate summary for a specific city, including best months to visit, safety profile, and monthly averages.

Parameter	Type	Description
slug	string (path)	City slug (e.g., prague, tokyo, bali)
minified	boolean (query)	Set to true to exclude daily data (smaller response for AI)

Example Request

curl "https://30yearweather.com/api/v1/city/prague?minified=true"

GET/api/v1/weather/:city/:date

Get weather data for a specific date (MM-DD format). Perfect for checking specific travel dates.

Weather for June 15 in Rome

curl "https://30yearweather.com/api/v1/weather/rome/06-15"

GET/api/v1/search

Find destinations that match specific climate criteria (e.g., "Where is it warm in May?").

Warm places in May with low rain

curl "https://30yearweather.com/api/v1/search?month=5&min_temp=20&max_rain_prob=30"

AI Agent Integration

Our API is optimized for AI agents, ChatGPT plugins, and LLM-based applications. Use these resources to integrate weather intelligence into your AI system.

OpenAPI Specification

Machine-readable API spec for automatic client generation and AI agent discovery.

/api/openapi.json

ChatGPT / GPT Actions

Use our OpenAPI spec to create custom GPT Actions. Import the spec URL directly.

https://30yearweather.com/api/openapi.json

Example: AI Agent Prompt

You have access to the 30YearWeather API. 
Use GET /api/v1/city/{slug}?minified=true to get city climate summaries.
Use GET /api/v1/search?month={1-12}&min_temp={temp}&max_rain_prob={prob} to find matching destinations.

When asked about weather for travel planning, use this API to provide 
30-year historical averages rather than speculative forecasts.

LLM Discovery Files

We provide machine-readable files for AI crawlers and LLM systems to discover and understand our data.

/llms.txt

Main LLM info file with service overview and API documentation

/llms-full.txt

Complete database of all 373 cities with coordinates and climate stats

/.well-known/llms.txt

Standard discovery location for AI crawlers

Pricing & Plans

CURRENTLY ACTIVE

Free / Developer

$0/mo

1,000 requests / day
All 373 cities included
Full API access
AI agent compatible
•
Attribution required

Pro API

TBD

•
Commercial License
•
Unlimited requests
•
No attribution required
•
Priority support

Bulk Data Downloads

For researchers needing large datasets without API rate limits, we provide pre-generated CSV exports.

Tokyo Historical Weather (1991-2021)

Complete daily records including temp, rain, and solar data.

• Format: CSV
• Records: 10,950 rows
• Size: 2.1 MB

Top 50 Cities Dataset

batch export of the world's most visited destinations.

• Format: CSV (Zipped)
• Cities: 50
• Size: 98 MB

Need a custom dataset?

We can generate custom exports for specific regions, time periods, or climate parameters for academic use.

Request Research Data →

Attribution Required

When using our free API, please include a link to 30YearWeather.com on any page or application where this data is displayed.